Various batteries have been proposed to date as a lithium secondary battery comprising silicon oxide in its negative electrode. For example, Patent Literature 1 describes, as preferable methods for preparing silicon oxide or silicate containing lithium, a synthetic method including mixing simple substance(s) or compound(s) of lithium, silicon, another metallic element or nonmetallic element, and the like in a prescribed molar ratio and heating in the air or an atmosphere containing oxygen, and a method including subjecting silicon oxide to absorb lithium ion thereinto by an electrochemical reaction between silicon oxide, such as silicon dioxide SiO2 or silicon monoxide SiO, and lithium or a substance containing lithium (Patent Literature 1, paragraphs 0011 and 0016).
Patent Literatures 2 to 7 describe that the silicon oxide preferably used as an electrode material satisfies that when a spectrum of the silicon oxide is measured by solid state NMR (29SiDD/MAS) with a sufficient relaxation time set, two peaks of a broad peak (A1) centered at −70 ppm and a broad peak (A2) centered at −110 ppm are separately measured, and an area ratio between these peaks (A1/A2) has a value falling in a range of 0.1≤A1/A2≤1.0.